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How to seal a skylight?

I have “older style” skylights in my ensuite bathroom and laundry that are causing ongoing issues. Originally I would notice leaves and debris in my shower and realised they were getting through gaps between the skylight and roof. No sealant or flashing tape was used when it was installed. So a few years ago I got up there and using sealant closed up all the gap between the frame and roof.

Now with a lack of ventilation mould regularly occurs, every 6 months or so I get up there and clean it. I’ve used vinegar solution, bleach and D-Mould (mouldicide) but it always returns. In winter I see a lot of condensation on the inside of the skylight, which I suspect is a major cause of this issue.

I’m interested in closing it off and turning it into a modern style “sun tunnel” but can’t find any info others doing the same?

I thought firstly I need to replace my roof mounted frosted skylight domes with a clear ( as UV helps kill mould).

Then I clean and paint the tunnel area (which is constructed of plywood boards) with mould blocker and possibly even install silver sark extra R value sheets? Lastly I close off the bottom with water-proof plasterboard and cut out a section to install a ceiling diffuser.

I think this would solve my mould issue and better insulate my house. I can see these items are available at Bunnings, any advice you can provide on this project would be greatly appreciated.

Thanks

Alex Grassedonio

Ensuite BathroomEnsuite Bathroom

Laundry SkylightLaundry Skylight

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Jewelleryrescue

Hi @alexgrass

Uv is blocked by most plastics clear or other usually just a quick note.

Moisture is your real issue as you meantioned yourself consider adding a exaust fan into the side wall of you tunnel and have it connected to the light switch so it runs while people use the bathroom Or a separate switch. Or I have used motion detectors in spaces like the ones off security lights you can get flat 360 ones.

I dont feel rebulding or adding a sun tunnel will solve moisture problem but some sky light vents modern ones are solar powered and will add ventilation as well .

CSR Bradford 250mm Woodland Grey AiroMatic Smart Roof Vent

$449

I/N: 0811143

EricL

Hello @alexgrass

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about your skylight.

Looking at your first picture, it appears that water and debris are entering the side of the galvanized flashing and is passing through underneath which leads me to believe that the seal you've placed above might have failed or has sprung a leak. I propose checking your roof flashing again and re-sealing it with Selleys Storm Roof and gutter Sealant. For the inside part of the flashing, I recommend using the clear version of Selleys Storm.

Now that you've sealed both the top and bottom part of the flashing, I recommend installing an HPM 100mm Square Slimline Wall Exhaust Fan in one of your walls. This will pull out all the moisture in your bathroom whenever you shower and keep the room moisture free.

Let me call on our experienced members @Dave-1 and @Nailbag for their recommendations.

If you have any other questions we can help with, please let us know.

Eric

Dave-1

Good Evening @alexgrass

I thought at first it was leaking 🙂 Phew!

After reading through your words and looking at the pictures I was starting to think along the lines of @Jewelleryrescue and @EricL with a fan installed to draw the mositure out of the room.

So first question - Does the room have a ventilation fan?

The condensation is what is causing those drips I am presuming so there isnt a leak from outside into the lightwell

Second question - Do leaves still come in?

I have what you are after 🙂 and you have what I am after! lol My bathroom has a smoked clear perspex at roof height then corflute above with tape to join the corners up to the clear plastic tiles! When I redo my bathroom it will be with what you have 🙂

I am thinking of closing off the bottom of you lightwell with a sheet of clear plastic. This is to keep the moisture out and to give the light access still.

Suntuf 600 x 1200 x 3mm Clear PVC Handisheet (If your sunwell is wider then the plastic fits you can get larger pieces of perspex elsewhere but I would suggest thicker then the 3mm will be needed if larger width is required otherwise it may bow.)

QEP 25mm x 2.5m Transition Cover Trim is what the trim that surround my lightwell looks like. The middle of the upside down T is fastened to around the edge of the cavity with diagonal cuts to form the rectangle of the hole. The perspex cover is cut a little smaller then the inner dimensions and to put it in you flex it a little an then push it up and then lay it back so it rests on all four inner edge of the upside down T.

Your bathroom will need an exhaust (mine has one as there is no windows) and then no more mould!

Dave

Nailbag

Hi @alexgrass

Skylights in bathrooms are not a great idea unless they are ventilated with something like as @Jewelleryrescue has highlighted. They allow hot moist air to rise and condense to eventually develop mould.

I would consider getting quotes on a new skylight that is ventilated. Then look at upgrading or installing a high-efficiency exhaust fan like "Pure". I'm not sure if these can be special ordered through Bunnings?

Nailbag

alexgrass

Thanks for the reply's,

In answering some questions,

*the gaps were between the skylight wooden base frame and top of tunnel shaft. These are manual opening skylights with hinges but they didn't seat well, now with sealant applied they are permanently "closed". No mores leaves/debris get inside the house and no water leaks either. The galvanised flashing/metal frame is pop-riveted around the plastic skylight dome to secure it and seems to be sealing fine.

*The ensuite bathroom is original and has no exhaust fan. I stopped showering in the ensuite years ago to prevent further humidity issues.

* The drip stains in the picture would be from in winter when we run the ducted heater, all the hot air rises into the tunnel and visually I see the skylights in the morning covered in condensation (both laundry and ensuite bathroom) and once I felt it drip on me. This is the main reason I want to close it all up, stop heat loss and make the house more energy efficient.

*In the main bathroom I installed a Panasonic DC Motor Exhaust with sensor which is great, but I didn't install the other in my ensuite bathroom yet. With the sensor detection angle I don't think it will work unless I walk into the shower or wave my hand up/near the skylight cavity). It would have to be run at low airflow setting continuously (which it does allow).

(Panasonic Ceiling Mounted Ventilation Fan With Motion Sensor - Bunnings Australia)

This is one project I've left to the side as I'm unsure which way to go?

Close it off at ceiling level with plasterboard/diffuser, then install the Panasonic Exhaust fan in the corner of the bathroom (same as main bathroom) but maybe the mould will return even worse.

Or leave it open as it is and install the Panasonic Exhaust in the tunnel on continuous low airflow setting.

One final thought is if I did close off the skylight tunnel I could fit white colour grill vents on each side of tunnel? My roof space is well ventilated already with eaves vents and a pair of Bradford CSR 250mm TurboBeam Natural Roof Vent - Clear - Bunnings Australia so then the airflow in my roof would help ventilate the closed tunnel.

Thanks

Alex

Dave-1

Morning @alexgrass

With vents in the light well you will always loose heat. When its windy my perspex skylight cover gets sucked up even.

I havnt seen a sensor style fan before, Ive only ever seen one that kicks in when the light is turned on. Maybe thats somethingto invistage for the ensuite?

Stopping the humidy rising and condensing up the lightwell should do away with mould.

Dave

EricL

Hello @alexgrass

Thanks for providing the extra information. My only added suggestion is that if you decide to close it off with a diffuser make sure that it can easily be removed for ease of maintenance. By using the diffuser, it will prevent heat from escaping in the tunnel. I propose placing the Panasonic Ceiling Mounted Ventilation Fan With Motion Sensor close to the center of the room rather than placing it in a corner where it will lessen its effectivity. This will also have the added benefit of the sensor being activated as you walk under the ceiling fan.

If you need further assistance, please let us know.

Eric

Jewelleryrescue

Hi @alexgrass

Taking a second look at your photos. I think @EricL might be right I think you do have a slight leak? Not meaning to worry you.

Not where you sealed the inside closer but between your sky light frame and the house those are black water run lines Maybe worth a revisit out side with some storm seal silicone on a bone dry roof so the silicone bonds and seals properly.

I could be wrong just keep it in mind if you see water drips forming when raining.

Hope it is not save you some mucking around.

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